The handling of optical fibers requires special care. This is particularly true in splice enclosures. Due to their size, which can be as small as 0.002" in diameter, the handling of fibers is a problem. Transmission capabilities will be impaired if a fiber is bent beyond the permanent bending radius, the point at which light is no longer totally contained in the core of the fiber. Furthermore, fibers are brittle and will break if bent beyond the minimum bending radius. Unconventional methods for the handling and storage of fibers must therefore be devised. While glass and silica (the materials used to make optical fibers) are in some respects stronger than steel, fibers normally do not possess this potential strength because of microscopic surface fractures which are vulnerable to stress and spread, causing the fiber to break easily. Thus the take-up of fiber slack in a closure presents a problem for multi-fiber cables, where individual fiber splices are required to facilitate rearrangements and repairs. Another problem is that of identifying individual fibers. In large multi-fiber cables each fiber must be readily identifiable for subsequent testing and repairs. Unlike copper where the insulation may be colour coded, coding is difficult with individual optical fibers.
In an attempt to mitigate these problems, a standard splice enclosure with a central transverse bulkhead was used. The individual fibers are spliced and are attached to the bulkhead for support. A disadvantage of this approach is that storage of slack in the fibers is not provided for. Furthermore, each of the fibers must be individually tagged for identification purposes.
Another approach uses a ribbon type optical fiber arrangement where twelve fibers are fixed together side by side. Twelve of these ribbons are then stacked one on top of another to obtain a cable containing 144 individual fibers. The fibers are bulk spliced using an epoxy technique and the cable is placed in a standard splice enclosure. Disadvantages of the above approach are the lack of access to individual fibers and, again, no slack storage. A single fiber failure is impossible to repair, and the fiber must be taken out of service.
In other splicing arrangements all the fibers in a cable are looped within the same retainer or fiber slack is stored on spools. In either case identification, repair or splice work of individual fibers is extremely difficult without a major shuffle in the splice enclosure. This is undesirable as transmission capability can be affected in working fibers as they are moved.
The present invention mitigates these problems by providing a device for organizing, segregating and protecting a plurality of individual optical fibers or other similar type conductors or fibers at a slack or splice point. A device having modular construction is provided which is suitable for installation in standard splice enclosures. The device comprises a plurality of tray-like members each adapted to retain and store the slack in at least one fiber. The device provides easy access to the individual fibers contained in the trays. Each tray is marked to identify individual fibers therein. The trays are stacked one on top of the other, and are each hinged separately at one side thereof to a carrier, thus allowing them to move relative to one another like bound pages. To provide additional capacity, the carrier structure is extended by adding to it and more trays are then stacked.
Thus in accordance with the present invention there is provided a device for organizing optical fibers and the like including a plurality of stacked traylike supports, having at least partially turned up edges for retaining a looped fiber portion, separately hinged at one side to a carrier and having a width at least equal to twice the minimum bending radius specified for that fiber.